The term `organic' is no longer used in DSM-IV because, according to the members of the `DSM-IV Workgroup on Organic Mental Disorders', it incorrectly implies that `nonorganic' mental disorders do not have a biological basis. The disorders, in DSM-III-R classified as `psycho-organic disorders', were moved to their fenomenological homebases without the adjective `organic'. In this article the developments leading to this change will be discussed. The changed meaning of the terms `organic' and `functional' in the past 150 years will also be discussed.